With increasing industrial development, diverse electronic devices are used to achieve various purposes. An electronic device comprises a plurality of electronic components. Generally, different kinds of electronic components are operated by using different voltages.
As known, a power supply is essential for many electronic devices such as personal computers, industrial computers, servers, communication products or network products. Usually, the user may simply plug a power supply into an AC wall outlet commonly found in most homes or offices so as to receive an AC voltage. The power supply will convert the AC voltage into a regulated DC output voltage for powering the electronic device. The regulated DC output voltage is transmitted to the electronic device through a power cable. Since different electronic devices have different power consumption magnitudes, the power factors indicative of the efficiency of utility power are usually different.
For increasing the efficiency of utility power, an additional power factor correction circuit is included in the electronic device in order to increase the power factor. Moreover, a multi-loop power factor correction circuit is used in high-power electronic device in order to achieve a better power factor correction function. Although the multi-loop power factor correction circuit is effective for increasing power factor, the overall volume of the electronic device is increased, which is detrimental to minimization of the electronic device. In addition, the utilization of the magnetic element used in the multi-loop power factor correction circuit is usually unsatisfied. In a case that the winding window of the magnetic element is beyond an acceptable range, only the magnetic core size, the diameter of the winding coil, the turn number of the winding coil or the copper slice thickness may be adjusted. In some situations, many magnetic elements are required. Too many magnetic elements occupy the layout space and are not cost-effective.